The 293 cell line is a permanent line established from primary embryonic human kidney, which was transformed with sheared human adenovirus type 5 DNA.  The adenoviral genes expressed in this cell line allow the cells to produce very high levels of recombinant proteins.  Invitrogen offers several variants of the 293 cell line, including those adapted for high-density suspension culture in serum-free media.

Healthy 293 Cell Morphology

The phase contrast images below show the morphology of healthy 293 cells in adherent culture at 80% confluency (Figure 3.1) and in suspension culture (Figure 3.2).  Note that adherent mammalian cultures should be passaged when they are in the log phase, before they reach confluence (see When to Subculture).

Figure 3.1:  Phase contrast images of healthy suspension-adapted 293 cells in stationary culture.  The cells were plated at a seeding density of 5 × 104 viable cells/cm2 in 293 SFM II medium and grown as an unattached culture in a 37°C incubator with a humidified atmosphere of 5% CO2 in air.  The images were obtained using 10X and 20X objectives (panels A and B, respectively) 4 days after plating.

Figure 3.2:  Phase contrast images of healthy 293F cells grown is suspension.  The culture was started in a shake flask at a seeding density of 2 × 105 viable cells/mL in 293 SFM II medium and grown in a 37°C incubator with a humidified atmosphere of 5% CO2 in air.  4 days after seeding, the cells were diluted 1:3, and the images were obtained using 10X and 20X objectives (panels A and B, respectively).